Root Architecture And Water Use Mechanism Of Tamarisk In The Extreme Arid Regions

The ecological water transfer has changed the long term dried-up of the lower reaches of the Tarim River, but a fairly thick dry soil layer still exists due to the limited income water from the upstreams and little rainfall and strong evaporation. Plants are difficult to survive in regions where the ground water level is too low. Tamarixchinensis, the dominant species and also constructive species, is a useful species in ecological restoration and sand precaution.This paper analyzed root architecture and water use mechanism of Tamarisk in the extreme arid regions using topological analysis of the root architecture and theisotope tracing of water source. The aim is to analyze the root architecture and water use strategy of Tamarixchinensis in the extremely arid environmentand to explain root growth and water use characteristics of Tamarixchinensis. This study could provide a scientific basis for the ecological restoration and the construction of windbreak and sand-fixation forest in the lower reaches of Tarim River. Following conclusions could be drawn:(1) The groundwater level of the study area is 300±10 cm. Soil layer between 0 and 50 cm or below 150 cm are easy to get water supply and. The soil water contentsin different months vary withthe soil moistureof the soil layer between 0 to 50 cm stays about 3%. The primary water-uptake layers of Tamarixchinensisis 180-270 cm, 120-240 cm, 150-240 cm, 120-210 cm in June July August and September, respectively, due to the variation of soil moisture. Tamarixchinensisuses water from deep soils for all months, but the demand differs due to the soil moisture: Tamarixchinensisuse water which is near to the roots when soil water can support its survival.(2) We classified the root system of Tamarixchinensis into 3 grades:d?5mm, 2 mm<d?5 mm and d?2 mm, and carried out regression analysis on contribution of each soil layer to Tamarixchinensiswater uptake. It showed that the root length of 2 mm<d?5 mm was positively correlated with the utilization of diverse water sources, which can well reflect the water use status of Tamarixchinensis.(3) Tamarixchinensis has a long root connection length, affected by age and living conditions. The adaptive strategy of Tamarixchinensis are influenced by the ages and living conditions. The topological structure of the root system changed with age and living condition.The manifestation has fishtail branch of root while four-year Tamarixchinensishas forked branch of root. In addition, drought tends to reduce the root branching. Overall branching rateof the Tamarixchinensis does not significantly influenced by ages and living conditions.